For many medical examinations and/or treatments it is advantageous or even necessary to detect and evaluate physiological parameters such as heartbeat or breathing and/or possible movements of a patient.
Examples cited here include captured images of the inside of the body of a patient by means of various modalities such as e.g. computed tomography or magnetic resonance tomography or also therapeutic treatments e.g. with a radiation therapy device The detected data about the physiological parameters of the patient and/or other movements of the patient during the capture of images are used here for example to adjust the acquired image data for movement or indeed to trigger the capturing of images. Frequently the data about movements and/or physiological parameters also provide important information as to a patient's health or state of mind, which can be a determining factor when planning the next course of action even during an examination or treatment.
In order to determine physiological data about a patient, the use e.g. of an ECG to determine the heartbeat, and of a breathing belt to determine breathing, is known. However the necessary application of electrodes and/or of the breathing belt always takes up a certain amount of time, which extends the examination. Moreover these steps are frequently felt by patients to be uncomfortable.
Another parameter that is to be monitored in order to optimize many medical examinations and/or treatments is the movement of the patient's body.
One known manner of monitoring movements of the patient is to arrange so-called light spots at relevant points on the patient, for example at joints and/or principal axis points, and to record the movements of these light spots e.g. with the aid of a video camera. The actual movement is suggested by the data captured in this way for example by means of movement models. This is not always sufficiently precise, since the actual movement of the body is not recorded, but instead movement data from several important measuring points is interpolated.
Moreover, in certain cases it is additionally expedient to monitor the environment of the patient, for example in order to avoid collisions with moving parts of a medical device. For this purpose the use e.g. of cameras in conjunction with object recognition software is known. However it is not always possible to position a camera such that the best-possible perspective on the patient and his/her environment can be achieved.
The radar technique is a known technique for contactless detection of the position and/or movements of objects by emitting electromagnetic signals and receiving signals reflected by the objects. In addition, passive methods are also known in which not reflected radiation, but instead a natural radiation emitted by all objects with a temperature higher than 0 Kelvin, is detected. Using this method temporal resolutions of less than one millisecond and spatial resolutions of up to one millimeter and more can be achieved (see e.g. “A Growing Number of Applications Boosts mm-Wave Technology”, High Frequency Electronics, Vol. 5(5), May 2006, p. 52 et seq.). A 3D radar sensor, with which a three-dimensional presentation of the detected objects is possible with a measurement, is known for example from DE 100 41 769.
A method for sensing information about the position and/or movements of a living organism or of part of the inside of a body, particularly for use in a motor vehicle, is known from DE 102 59 522 A1. An objective of the method described in the aforementioned publication is to monitor the breathing and heartbeat of a passenger during a journey.